Safety attachment for punch presses



Nov. 24, 1931. 1 1 w Q ANG 1,833,840

SAFETY ATTACHMENT FOR PUNCH PRESSES Fi1ed March 1, 1929 2 sheets-sheet 1 i? a H f s /f FV @Q if *50M/ff /7 /5 3 f7 l lll/ /9 1:? w l/ y .f1/f 4 e 4' I' 'E5- ll 56 I 3 l" 11 A 1. 1 35 i o O07 gx 4,/ 05;/ o o oo \\\\\74zv 5, j r r 75 7a 5 7g 75 I7/ 7969 74 7 55 70 5 il 74 5 5 1 Il 1 6 JIL :i

il. (I l :A: ,I Il Il me/niet Williamllang (ummm, l

Nov. 24, 1931. w. c;t LANG 1,833,840

SAFETY ATTACHMENT FOR .PUNCH PRESSES Filed March l, 1929 2 Sheets-Shee 2 S11/vento@ mmnnl Willimlang Patented Nov. 24, 1931 UNITED STATES WILLIAM G. LANG, F WASHINGTON, DISTRICT O1?` COLUMBIA SAFETY ATTACHMENT FOR PUNCH PRESSES 4Application filed Marchv 1,

This invention relates to safety means for clutches in power presses, punches and similar machines. j Y

In certain types of presses and punches the 'f '5 operator places work in the press and operates a-pedal to start the press. rIhe pedal throws in a clutch which connects a driving with a driven part of the machine to cause the press or punch to make one cycle of oper- 19 ation, whereupon the clutch is operated to disconnect lthe press from the source of power. Solong as the clutch remains inltact these machines operate with safety to l 'the operator. If, however, the key element --l5 in the clutch becomes broken the means which releases the clutch fails to function to disconnect the driving and driven elements of the machine. This frequently happens and not infrequently, also, the operator thinking 50 the machine is stopped puts his hands beneath the press to put an additional piece of work in position, with the result that his hand is caught beneathv the press and seriously injured.

The device forming the subject matter of this invention seeks to safeguard presses in this respect, by providing a safety device which will stop the machine in case the clutch key becomes broken. So long as this key is uninjured the machine will operate in safety without my device playing any part in the operation. As soon, however, as the key is broken, the mechanismvwhich normally releases the key to disconnect the driving and driven mechanism fails to function. My device then automatically comes into play to stop the press.

In presses of the kind just described the operatorsometimes fails to release the pedal after pressing it down.V `This causes the machine'to make more than one stroke. A further safety feature consists in mechanism which will stop themachine even if the operator keeps his foot on the pedal. 45 Referring to the accompanying drawings which are made a part hereof, and on which similar reference characters indicate similar parts,

Figure 1 is a front elevation of a press hav ing my safety device applied thereto,

1929. Serial 110.3113398.V

Figure 2 is a side elevation with the main flywheel and certain other parts removed, as 'seen substantially on line 2-2 of Fig.j 1,

Figurev 3 is an enlarged sectional view, Vshowing the clutch key inlocked position, Y ,l

Figure 4' is a sectionfon line 4?-4 of Fig. 3, Figure 5 is a detached view of one ofthe safety-devices,

Figure 6 isa cam,

keys i f Figure 8 is a detail view of the clutch releasing means, and

Figure 9 is a detail plan view ment shown in Figure 8. l j

Referring to the drawings, reference` character 10 indicates the supporting legs `of a press having anof-set bent over ar'm\11 of the elewhich carries a motor'12 supported on brac'k- 7' nected to a reciprocating punch shaft 2() carrying on its'lower endapunch 21 which co-operates with an anvil 22. -The drive whe-e117 is locked to ther driven shaft 16. by means of akey A23 which slides ina slot 24 in the shaft 16. The key 23 engages a slot 25 inthe side of the drive wheel 17. Hardened plugs 26 are pressed into holes in the drive wheel and Ycut ofi' at "27 to provide a harden-ed surface against which the keyr 23 perspective view of the safety Figure7 perspective view ofthe clutch i engages.A Th-e key 23 is. urged into locking position by means` of a `spring'28 seated in a bore in the key.V `The spring surrounds and f is preferably guided by means of a. short rod 30 which is secured by a pin29 to the shaft v 16. The key 23 has yon one side a notchv 31. One side of the notch is cut to provide a cam surface 32, which surface isA engaged by a releasing dog which withdraws the key from locking connection with the drive wheel, as will be more fully described. The shaft 16 has an enlarged collar 33 which is engaged by a brake drum 34 which drum is kept normally tight enough to allow the shaft 16 to rotate when driven by th-e fly wheel 17, but which will immediately stop the shaft when the shaft is disconnected from the driving wheel. Each rotation of the iyv wheel 17 causes the punch to make one cycle of operation. With each cyclethe key is withdrawn from looking connection with the fly wheel 17. The means for withdrawing the key will now be described. Pivoted on the frame ofthe machine at is a lever 36. This lever has onl its outer end a beveled edge 37 which engages the camedge 32011 the key 23 to withdraw the key when the leverl is in its uppermost position. YA compression spring 38 surrounding a guide rod 39 secured to the lever 36 normally urges the lever upwar-d.` The rod 39 is. guided' through a hole in a bracket 40 secured upon the standard 11.l The outer end of' the lever 3.6'has a depending notched portion 41 .by means of which the lever is pulled down against the tension of the spring 38. A rod 42 is slid- .ably mounted between gui-deways 43 and 44 25 secured to' the framework of the machine.

A latch 42" is pivoted .to this rod. This latch 42 has its upper endfnotched at 45 to pro- .vide a hook' fory engagement with the 'notch 41 on the lever 36. A block 46 is secured to the endof the latch 42 by means of a bolt or screw 47, the upper end of the block 46 eX- tending up beyond the'cen-ter of the shaft 16. This block is held inengagement with the periphery of the lshaft by kmeans of a tension kspringf48. A lever 49is pivotally secured to the frameof the machine at 5.0 and is pivoted at 51 ,to the block 42. A rod 5.2 is hooked in theouter end of the lever 49 and connected .te a foettreadl'e 53. A tension .spring .54 tends to hold the foot treadle '53 in an elevated position. A block 61 is secured to the latch 42 beneath the end ofthe lever 36. The purpose of this is to enable the latch42V tolift the end of the lever 3.6 in case the spring 38 fails to operate. When the operator wishes .to start operation of the ma- .chine lhe presses down upon the pedal This pulls down the bar 42 and latch 42 and :by means of the notches and 41 pulls down the ylever 36 to withdraw ythe edge 37 .from engagement with ythe cam edge .32 .of the key 23. As the drivewheel rotates to `.bring either of theslots 25 opposite the end of thekey, the key is driven into the notchv to l key the shaft and drive wheel together to rotate the shaft to operate the punch` As the key again 4reaches the edge 37 of .the lever 36 this edge acts as a dog towithdraw the key from engagement with the drive wheel .and stops rotation ofthe shaftl. y y

.In operation, the 4operator `presses the pedal `53 as just described.A This causes the press to make one operati-on. kIn vpresses as formerly constructed, .should the operator keep his foot on the pedal, the press would continue to operate7 and if the operator'inadvertently put his hand beneath the punch, forgetting that he had his foot on the pedal, his hand might be injured.

How the structure just described will pre vent the machine from operating even if the operator continues to hold down the pedal 53 will now be explained'. The .block 46 just described is held in Contact with the shaft 16 riding in an annular channel 56 on the shaft. As the key 23 reaches 'the position representabout three fourths of a revolution from the starting point shown in Fig. 2, it strikes the bar 46 which pushes the latch 42 to cause the notch 45 to release the notch 41 and allow the lever 36 to move upward to lthe position where will engage the key 23 `when the shaft has rotated another quarter revolution. The operator may continue to hold the pedal down without endangering himself. It will be seen therefore that my device will cause the press to make only one opera-tion unless the operator definitely presses the pedal to cause a .second operation.

The impact which thekeys 23 have to receive starting the machine subjects them to enormously heavy duty. Due to crystallization/of the metal or to metal fatigue or other causes, these impacts sometimes break the key-s. When this happens the spring 28 pushes the br-okenfolil end of the key into the notch to connect the driving wheel with the :shaft 16. Moreover, the releasing dog .37 under .these circumstances does rnot operate v4to withdraw the key at each rotation of the shaft 16. A broken key'therefore not infrequently causes the punch to .be driven down to catch the hand-of the operator to injure him. Means for withdrawing the key when it has become broken will now be described: .Positioned in axial bores in the hub of the drive wheel 17 are pins 57 and 58. A cap 59 is screw threaded on the outer end of the shaft 16. This cap is secured against rotation by means of a screw -60 which is threaded in a bore cut partly in the cap 59 and partly in the screw threaded end of the shaft 16. A plate f62 is fastened to a :depending bar 63 which bar is secured to Va bracket 64. The plate -62 is provided with a slot 65 having v plates 66 and 67 -secured on each side'in order to support a cam 68. A 'rod 69 has its upper end positioned in Ia hole in the vcam 68 and is secured at its otherend by means of a bracket 70 to the rod 52. A plate 71 is secured by means of a screw 72 to the cam 68 which plate holdsthe end of the rod `69 in position in the cam 6'8. The forward edge of the inner end of the "cam 68 is cut to provide a wedge shaped surface 73. The operation the inner end of the cam 6.8. This Vwedge edge moves the pin axially to push out the key 23 from the slot 25 in the opposite edge of the pulley 17. If therefore' the key has been broken so that the dog 37 will not withdraw it when it reaches the lowermost position,

the inner end of the key will be pushed outV by means of the cam 68 acting against the end of the rod 57 or 58, so that the punch or press will be stopped in the elevated position. The rods 57 and 58 cannot possibly fail to push out the key, since it is impossible for the pulley 17 to rotate Without the end of the rod 57 or 58 riding the cam edge 7 3.

In order to prevent operation of the press when the operators hand is beneath the press, I have provided safety means as follows: Bars 74 are pivotally mounted on brackets 75. Secured at the outer ends of the bars 74 are depending rods 55. These rods are secured in a ring plate 76. A compression spring 77 is positioned between the upper end of the plate 76 and the bracket 75. A rod 78 is rigidly secured to the bars 74 and has on its outer end a rock arm 79. This rock arm is connected by means of a rod 80 and a. bracket 81 to the rodl 52. `Ihen the pedal 53 is pressed down it carries with it the rod 52 and the rod 80 to swing the rock arm 79 to swing the disc 76 to the position which the work assumes. If the operators hand should be placed on the anvil 22, the disc 76 will strike his hand so that the pedal 53 cannot he pushed down sufficiently far to pull down the Vdog 37 so as to release the key 23. It will clearly be seen therefore that whenever the operators hand is in the position in which it might be injured by the punch or press, he cannot start the press.

It will be obvious to those skilled in the art that various changes may be made in my device without departing from the spirit of the invention, and I, therefore, do not limit myself to what is shown iii the drawings and described in the specification, but only as set forth in the appended claims.

Having thus fully described myv said invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a power press having a driving and a driven element, a slidable key for connecting the driving With the driven element, means for sliding said key axially to disconnect the driving from the driven element at the completion of each revolution, and means operable upon a breaking of said key to disconnect the driving from the driven element, substantially as set forth.

2. In a power press having a Vdriving and a driven element, means for clutching the driving element to the driven element com* prising a key in said driven element, means for axially moving said key at a predetermined period in each cycle of the press to disconnect the driving and the driven elements, and means in said driving element operable only upon a breaking of said key to axially move said key to disconnect the driving from the driven element, substantially as set forth.

3. In a power press having a driving and a driven element, clutch mechanism for connecting the driving with the driven element comprising a key in said driven element sli dable axially to connect the driving with the driven element, means operable at a predetermined position of the driven element to move the key axially to disconnect the driving and driven elements, and means in said driving element operable to move the said key axially in case the said last named means fails to function, substantially as set forth.

4. In a power press having a driving and a driven element, an axially movable key mounted in said driven element for connect ing the driving with the driven element, plungers in the driving element, a manually controlled cam operable at a predetermined radial position of the plungers to move one of the plungers axially to disconnect the said key from the driving element in case this key is broken or otherwise fails to function, substantially as set forth.

5. In a power press having a driving and a driven element, a clutch key for connecting the driving with the driven element, means for releasing said key to connect the driving and the driven element comprising a horizontally disposed bar pivoted at one end and having a cam surface at the opposite end adapted to coact with said key, a hook adjacent said cam, a vertically disposed bar pivoted at its lower end and having its upper end in the path of movement of said key, a

hook on said vertical bar adapted to coact with said hook on said horizontal bar, and manually operated means to disengage said cam from said key topermit the release of said key and rotation of said driven element by said driving element until said cam is released to re-engage said key by contact of said key with said vertical lever, substantially as set forth.

6. In a press having a driving and a driven element and a key positioned inthe driven element and adapted to engage the driving element for keying the two together and having means for normally disengaging said key, auxiliary means operable automatically to push the said engaging means out of engagement with the driving element when the said Vengaging means becomes broken so as nor- WILLIAM G. LANG. 

